Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000
FXUS63 KDTX 171105
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
705 AM EDT Thu May 17 2018


.AVIATION...

Weak frontal boundary will slip into the forecast area today while
stalling and washing out. No moisture of consequence with this lower
tropospheric feature with strongly anticylonic flow across the
boundary and well organized subsidence bubble overspreading the
region. Main item for today is gusty northeasterly flow of 10 to 20
knots. Strong surface high pressure will grip the area tonight.

For DTW... Northeasterly flow operations with northeast wind of 10
to 20 knots.

.DTW THRESHOLD PROBABILITIES...

* None.

&&

.PREV DISCUSSION...
Issued at 344 AM EDT Thu May 17 2018

DISCUSSION...

Weak flow across the conus as an upper trough over the western
states aides in ridging over the eastern Rockies and Plains. This
ridge is deflecting the northern stream of the jet well to the north
over northern Canada. The southern stream remains on the weak side
though attempts to flare up at times as slightly stronger shortwaves
advance through the flow. Weather will be quiet through the end of
the week as confluent flow aloft works with building surface ridge
to produce a stable environment. Chances of precipitation return
this weekend as an upper level trough sets up over the southern MS
Valley with a good feed of Gulf moisture extending up into southern
MI.

For today, a surface low that raced across Ontario Wednesday, is
pulling a cold front through the state. The front is losing its
forward propagation over Mid MI as the parent low is nearing the
Atlantic coast already this morning. The dry airmass in place with
the weakening ridge in over southern MI will prevent any chance of
precipitation with this front, but as shown in the obs overnight,
scattered clouds may reach the area before scouring out. Bigger
impact of the front will be the enhanced northeasterly flow in it`s
wake. Winds will increase to 20 to 25 knots off Lake Huron today
which will keep the lakeshore areas about 10 degrees cooler that
locations inroads. Other concern is the enhance wave action into the
eastern shore area of the Thumb. With the water table around 3 feet
higher than datum, waves around 4 to 8 feet may create issues for
the shoreline thus the Lakeshore Flood Advisory was issued last
night.

Strong surface high will settle into the northern lakes behind this
front Friday resulting in eastern flow through much of the coming
weekend. Meanwhile the aforementioned upper level trough will pull
moisture and possible surface low up into the Ohio Valley. Models
have been pretty consistent keeping Friday dry as the elevated
moisture on the northern flank of the system gets scoured out by the
dry ridge in place. Looks like the first big surge of moisture will
arrive after 00Z Saturday along with a band of vorticity releasing
from the trough. Pops get introduced for Friday night. With the bulk
of the moisture plume off to the east, not too confident with
coverage so will keep a chance pop. The upper trough and surface
reflection then begin to advance NE skirts SE MI. Unsure at this
time how far NW into MI the moisture and showers will actually
advance. So will continue to ride chance pops through Saturday
night.

Confluent flow sets up farther west on Sunday which then attempts to
direct the next low across southern MI. Though there are low chances
of elevated thunderstorms on Saturday, better chances for convection
look to come Sunday as the warm sector with this next low lifts into
clipping us with unstable air. Chance of Thunderstorms forecast for
Sunday.

Temperatures will hover in the 70s through most of the forecast
outside of shoreline areas as mentioned before. Fluctuations will
occur due to excessive cloud cover and possible warm sectors passing
through the area but overall expect 70s through the forecast.

MARINE...

A cold front of moderate strength will move southward across Lake
Huron early this morning. Wind shifting to northeast and increasing
into the 20 to 25 knot range is projected to generate 4 to 6 foot
waves along the Thumb shoreline with occasional wave height of 8
feet by Thursday afternoon into Thursday evening. Small Craft
Advisories are now in effect. In addition, the already high
undisturbed Lake Huron water level along with the high wave action
raises potential for minor lakeshore/beach erosion with damage to
recreational boating structures and/or watercraft anchored to the
shoreline. A Lakeshore Flood Advisory is in effect to raise
awareness on the hazard.

PREV DISCUSSION...
Issued at 1053 PM EDT Wed May 16 2018

MARINE...

A cold front of moderate strength will move southward across Lake
Huron late tonight through Thursday morning. Wind shifting to
northeast and increasing into the 20 to 25 knot range is projected to
generate 4 to 6 foot waves along the Thumb shoreline with occasional
wave height of 8 feet by Thursday afternoon into Thursday evening.
Small Craft Advisories are now in effect. In addition, the already
high undisturbed Lake Huron water level along with the high wave
action raises potential for minor lakeshore/beach erosion with damage
to recreational boating structures and/or watercraft anchored to the
shoreline. The Lakeshore Flood Advisory is added to the forecast
update to heighten awareness on the hazard.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...Lakeshore Flood Advisory until 10 PM EDT this evening for MIZ049-
     055-063.

Lake Huron...Small Craft Advisory until 10 PM EDT this evening for LHZ421-422-
     441>443.

Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&

$$

AVIATION.....CB
DISCUSSION...DRK
MARINE.......CB


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at www.weather.gov/detroit.



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